Architecture and Geometry of Basal Sand and Gravel Deposits Including the 'Grimshaw gravels', Northwestern Alberta (NTS 84C and 84D)

This open file report provides an updated geological framework of basal sand and gravel units in the Grimshaw area of the Peace River Lowland of northwestern Alberta, including their geometric distribution and stratigraphic history. It also includes an updated hydrogeological assessment of the 'Grimshaw gravels' based on recent data from the Alberta Water Well Information Database (AWWID) and a summary of the aggregate resource potential within the study area based on the updated geological framework. The geological framework is constructed by examination of subsurface geological data collected in the field and interpreted from AWWID lithology logs, oil and gas well logs, and previously recorded outcrop and borehole logs.

Three basal sand and gravel units are identified in this report: the Grimshaw gravels, Old Fort gravel, and Shaftesbury gravel. These units are mapped on a regional scale, which allows correlation to previously described units in the adjacent NTS 94A map area in British Columbia. The 'Grimshaw gravels' deposit in northwestern Alberta hosts an important producing aquifer (the Grimshaw gravels aquifer) and aggregate resource for the surrounding communities.